Caracterização físico-química e de potencial de produção de biogás da cama de sistema de confinamento de bovinos de leite

Abstract

Brazil is the third largest milk producer in the world, with around 35 billion liters per year, with more than 1 million milk-producing properties. The country has four central cattle production systems: extensive system, semi-extensive, intensive pasture, and intensive confinement. The intensive confinement system studied in this work is the Compost Bedded Pack Barn, which provides the most significant animal welfare, improving milk production. This system consists of an open area common to all animals and a handling track. The open area consists of a bed made up of organic material and manure. The objective of this present work was to study the characterization of this bed and analyze its capacity to produce biogas, estimating the biochemical potential of methane (PBM), enabling a new value-added destination, as it is currently treated as fertilizer. In the physicochemical characterization analyses, analyses of total, volatile, and fixed solids were carried out, obtaining the SV/ST value in the range of 75.4% to 84.6%, and the phosphorus analysis resulted in 5.765 mg kg-1 of total phosphorus. Total nitrogen and Kjealdahl analyses were also carried out, resulting in a sample of 671.194 mg kg-1 of ammoniacal nitrogen and 1.29% of total nitrogen. In the PBM test, the compost barn litter sample was inserted into the inoculum and remained for around 40 days in the semi-continuous agitation bioreactor. This process achieved an accumulated biogas production of 78 mL and a final biogas production of 0.021609 m3 Kgsv_added. This work showed that adding value to the waste generated in the compost barn system is possible, which produces biogas to self-sustain the property.